Conventional bearing apparatuses including bearing surfaces that move relative to one another are known in the art. For example, conventional, so-called “thrust bearings” and some embodiments of radial bearings include bearing surfaces that at least partially contact and move or slide relative to one another. Such bearing surfaces may include a superhard material for resisting wear during use of the bearing. In one example, diamond (e.g., polycrystalline diamond) may comprise at least one or both of the bearing surfaces.
More particularly, one application for bearings is drilling equipment utilized in the subterranean drilling arts. Particularly, drilling motors and drill bits with moving members, such as roller cones have been utilized for drilling boreholes into a subterranean formation, especially for oil or gas exploration. In a typical downhole drilling motor, the motor is suspended at the lower end of a string of drill pipe comprising a series of pipe sections connected together at joints and supported from the surface. A rotary drill bit (e.g., a fixed cutter drill bit, roller cone drill bit, a reamer, etc.) may be supported below the drilling motor (via pipe sections, drill collars, or other structural members as known in the art) or may be directly connected to the downhole motor, if desired. Drilling fluid, which is commonly known as drilling mud, is circulated through the pipe string and the motor to generate torque within the motor for causing the rotary drill bit to rotate. Then, the drilling fluid is returned to the surface through the annular space between the drilled borehole and the drill string and may carry the cuttings of the subterranean formation to the surface.
Further, as known in the art, mechanical systems may include radial bearings. For example, conventional downhole drilling may employ radial bearings. In one embodiment, an inner and outer race are each provided with a plurality of superhard bearing elements (e.g., polycrystalline diamond elements). The races are positioned adjacent one another so that the bearing surfaces of the bearing elements contact one another. As may be appreciated, geometry and configuration of the bearing elements of the races may be an important factor influencing the performance and life of such a bearing structure. Examples of conventional radial bearing apparatuses are disclosed by U.S. Pat. Nos. 4,662,348, 4,729,440, 4,738,322, 4,756,631, and 4,764,036, the disclosure of each of which is incorporated, in its entirety, by this reference.
Thus, it would be advantageous to provide improved bearing elements and bearing apparatuses including same.